慕哥，help~

来源：2-3 实体类设计与表创建B

繁星之夜

2018-05-19

慕哥，为什么我在建立微信账号表的openId唯一索引的时候，显示[Err] 1071 - Specified key was too long; max key length is 767 bytes啊。我字段是varchar（1024），引擎是innodb，mysql5.5，数据库表设置和你一致就是alter加索引的时候报错。怎么解决啊

create table `tb_wechat_auth`(

`wechat_auth_id` int(10) not null auto_increment,

`user_id` int(10) not null,

`open_id` varchar(1024) not null,

`create_time` datetime default null,

primary key (`wechat_auth_id`),

constraint `fk_wechatauth_profile` foreign key(`user_id`) references `tb_person_info`(`user_id`)

)engine =INNODB auto_increment=1 default charset = utf8;

alter table tb_wechat_auth add unique index(open_id);

[SQL]alter table tb_wechat_auth add unique index(open_id);

[Err] 1071 - Specified key was too long; max key length is 767 bytes

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